1. Field of the Invention
The present invention relates to relates to a liquid crystal display device, and more particularly, to a multi-domain liquid crystal display device in which a common auxiliary electrode is formed around and/or within a pixel region on a layer equal to a gate line, and a dielectric structure for distorting electric field, an additional dielectric structure or an electric field window are formed within the pixel region together with the common auxiliary electrode.
2. Discussion of the Related Art
Recently, a liquid crystal display device which drives a liquid crystal by an auxiliary electrode electrically insulated from a pixel electrode without aligning the liquid crystal has been suggested. Such a related art liquid crystal display device will be described with reference to FIG. 1.
FIG. 1 is a sectional view of a unit pixel of the related art liquid crystal display device.
As shown in FIG. 1, the related art liquid crystal display device includes a first substrate, a second substrate, a plurality of data lines and gate lines, a thin film transistor, a passivation film 37, a pixel electrode 13, and an auxiliary electrode 21. The data lines and gate lines are formed on the first substrate lengthwise and crosswise to divide the first substrate into a plurality of pixel regions. The thin film transistor is formed in each pixel region on the first substrate and includes a gate electrode, a gate insulating film, a semiconductor layer, an ohmic contact layer, and source/drain electrodes. The passivation film 37 is formed on the whole first substrate. The pixel electrode 13 is formed on passivation film 37 to be connected with the drain electrode. The auxiliary electrode 21 is formed on the gate insulating film to partially overlap the pixel electrode 13.
The related art liquid crystal display device further includes a light-shielding layer 25, a color filter layer 23 formed on the light-shielding layer 25, a common electrode 17 formed on the color filter layer 23, and a liquid crystal layer formed between the first substrate and the second substrate. The light-shielding layer is formed on the second substrate to shield light leaked from the gate lines, the data lines, and the thin film transistor.
An open region 27 may be formed in the common electrode 17 to distort electric field applied to the liquid crystal layer. The auxiliary electrode 21 formed around the pixel electrode 13 and the open region 27 of the common electrode 17 distort electric field applied to the liquid crystal layer so that liquid crystal molecules are variously driven within a unit pixel. This is intended that a dielectric energy by the distorted electric field places a liquid crystal director at a desired position when a voltage is applied to the liquid crystal display device.
However, the liquid crystal display device requires the open region 27 in the common electrode 17 to obtain multi-domain effect. To this end, a process for patterning the common electrode is additionally required.
Furthermore, if the open region 27 is not formed or has a small width, distortion range of the electric field required to divide the domain is weak. Accordingly, there is a problem that the time when the liquid crystal director reaches a stable state relatively becomes longer. Moreover, the electric field strongly occurs between the pixel electrode 13 and the auxiliary electrode 21. This increases luminance in only a portion, and also increases response time.